图,D是△ABC一边BC上一点,连接AD,使△ABC∽△DBA的条件是( )
A:AC:BC=AD:BD
B:AC:BC=AB:AD
C:AB2=CD•BC
D:AB2=BD•BC
关节既牢固又灵活,与此功能无关的是( )
The post office is ________ the park.